After an IC chip has been mounted on a lead frame chip carrier, and electrically connected to the leads thereof, it is often packaged in encapsulating material. Such packaged chip-containing lead frames are shown in, for example, the following U.S. Pat Nos.: 4,331,831; 4,301,464; 4,298,883; 4,264,917; 4,214,364; 4,132,856; 4,124,864; 4,079,511; 3,978,516; 3,793,474; 3,684,464; 3,659,821; 3,611,061; 3,436,810; and U.S. patent application Ser. No. 584,080; filed Feb. 27, 1984, the teachings of the latter application being incorporated herein by reference.
As pointed out in the above, the lead frames are usually made by stamping or etching metal strips. Where the manufactured quantities are sufficiently great, stamping is preferred because of its lower cost.
To fabricate the IC package, a plurality of electrically conductive lead-ins are attached to an electrically insulating base or substrate. An IC chip is then affixed to the base and electrical connections made between the chip and the lead-ins. A cover of similar insulating material is then affixed to the base and a sealant is provided between the base and cover to environmentally protect the chip. The sealant can be injected in fluid form as described in the above-identified application or it can be employed as a self-supporting medium as described in Ser. No. 659,212, filed Oct. 9, 1984. While each of these methods and techniques work, they occasionally present control problems in consistency of the seals.